Low-pressure steam generating system



Feb- 5, 1952 E. P. WORTHEN ET AL Low-PRESSURE STEAM GENERATING SYSTEM 3 Sheets-Sheet l Filled Oct. 4, 1946 Nw Y NA@ SW GGG Feb- 5, 1952 E. P. woRTHl-:N ET AL 2,584,651

LOW-PRESSURE STEAM GENERATING SYSTEM Filed Oct. 4, 1946 5 Sheets-Sheet 2 ZZZ A w, 10?4103 Febl 5, 1952 E. P. WORTHEN ET AL Low-PRESSURE STEAM GENERATING SYSTEM 3 Sheets-Sheet 5 lhs/anfang' E fuel? form anim Af' zwy Filed oct. 4, 1946 Patented Feb. 5, 19:52 Y

UNITED srA'r LiOVV-ERSSURE STEAM GENERATING SYSTEM Eugene Porter 'Worthem Braintree, and Benjamin Fox,"Woilaston, Mass.,'assignors 'to Bethlehem Steel Company, a corporationof .Pennsylvania Application cteber 4, 1946Serial No. 701,224

This invention relates in general to a system for generating low pressure steam, and more particularly to an auxiliary low pressure steam-system especially adapted for marine use -andcompletely isolated from the high pressure steam system.

The increasing use on modern ships of very highsteam pressures, in the neighborhood of 1500 pounds or more per square inch, is'attributable to the markedadvantages in thermal eliciency,

fuel economy-and speed when such pressures are applied to-main propulsion; but high `pressures are obviously unsuitable for most Yauxiliaryspurposes, such` as supplying-steam for various-heat-v ingservices or for deck machinery. Large passenger vessels, for instance, require large amounts oflow pressure steam for-heatingfand galley purposes. vOtherspecial types 'ofvessels'such'as oil tankers, which cannot use electrically'driven-deck auxiliaries with safetybecause ofthe relhazard, must operate suchauxiliaries v.as-mooringWinches, hatch cover Winches, and anchor Windlasses with 10W pressure steam. lThe exhaust steam from equipment of this type may carry large quantities" of lubricating oil and greasewhich mustbefprevented .from enteringthe main boiler feedsystem,.and steam drainsfrom fuel oil heaters-andotherheatingservices may also-be contaminated, so fthat a lowpressure steamsystem--safely and completely isolated ifromhthe main steam system is necessary.

While such' systemscan f be supplied-With steam cost as compared vwith a separately l red Arsteam.

generating unit.

Another object' is ra Alovt7 `.pressure steam` system i provided with automatic pressure regulating valves and level controllers andrequiring-a min-- imum lof attention by the operatingl force.

A1 further object is'a 10Wl pressure steam generator having a large water storagescapacityfgand thereby able ato meet '..suddengdemands .ffcr steam.

`5 `Claims. (Cl. (iO-95) in excess of rated capacity with very Vslight drop in steam pressure.

Still another object is a low'pressure steam system characterized by very low maintenanceA charges and a minimum of effect on the propul- 1 sion cycle.

Other objects, purposes and advantages `of the invention will appear-hereinafter in the speciiication and in the `appended claims, and invorder to render the same more clear We shall now refer to the annexed two sheets of drawings in which like characters of reference indicate like parts:

Figurefl is a diagrammatic view of the combined high and low pressure systems;

Fig. 2 is'avdiagrammaticview of.the low pressure steamgenerating system alone;

Fig. 3 is a longitudinal sectional View of 'the low -pressure 4steam generator;

lFig. 4 is a top plan viewof the drain cooler, with inner and outer shells partly broken away to show-the tubes;

Fig.5 is a transverse sectional view taken on the line 5-5 of Fig. 4 across the feed inletand outlet connections of the drain cooler;

Fig. 6 is va transverse sectional view taken'onA the line 6 6 of Fig. 4;

Figf'l'is a `transverse sectional view taken on the'line l-l across the side inletconnection of thedrain-cooler for admitting drains from the low-pressure steam generator; and

Fig. Sisan end View of the drain cooler with the end cover plate removed.

Referring-now tothe-diagrams, the pip-ing system .for high pressure steam is shown in heavy solid lines, that for high pressure condensatein heavy Adashed lines,.that for low pressure steamv in lightsolid lines, and that for low-pressure con-` densate in light .dashed lines, the direction of flow in each casebeing indicated by the arrows.v

As shown in Fig. 1,'the high pressure steam (about 1450 poundsper squareinch) generated in the drum .boiler l flows through the superheater 2 and conduits ...3,4, 5 vand .6 to vsupply directly the high pressurepropulsion turbine 1the reheaters 8 and 9 andtheturbo-generator l0, and through :the Aconduit I'l themain feed pumplZ. Because vof ,the high saturation temperature of the steam, rand-to obtain minimum'gas outlet temperatures and optimum efficiency, an air heater I3 :and aV feed Water economizer Ylli inthe boiler I -using the flue gases for heating are provided. A desuperheater l5 located lbelow the waterlevel in the drumboiler il and drawing boiler steam through the conduit I6 supplies Vva 400.pounds;per squareinch auxiliary steam line I1 via the conduit I8 and the pressure-reducing or throttle valve I9.

From the high pressure turbine 1, the propulsion steam passes through the bleeder connecting line 20, the high-pressure steam reheater 8, the intermediate pressure turbine 2 I, the bleeder connecting line 22, the 10W-pressure steam reheater 9 and the low pressure turbine 23 to the main condenser 24. Reheater drains are pumped by motor-driven drain pumps 25 and 26 through conduits 21 and 28 back to the boiler` Drains from the turbo-generator I pass to the auxiliary condenser 29.

The condensate and low-pressure feed system includes a first-stage combination feed heating unit of the type described in the United States patentl to E. P. Worthen, No. 2,328,044, issued August 3l, 1943; a feed Water drain collecting tank 30, and a second stage deaerating feed heater 3|.

The above-mentioned first-stage feed heating unit is a closed type unit combining Within one shell the auxiliary air ejector intercondenser 32, the main air ejector intercondenser 33, the feed heater drain cooler 34, the combined gland exhaust condenser and main and auxiliaryl air ejector aftercondenser section 35, and the first stage feed heater section 36, which are arranged in the shellfrom bottom to top in the order named.

The combined first stage unit receives the separate condensates pumped from the main and auxiliary condensers 24 and 29 by motor driven Vpumps 31 and 38 through conduits 39 and 40; and

discharges the combined heated condensates to the second stage deaerating feed heater 3|. The main condensate flows through the tube passes of the main air ejector intercondenser 33 and the feed heater drain cooler 34, while the auxiliary condensate ows through the auxiliary air ejector intercondenser 32 and combines with the main condensate at the entrance to the combined main and auxiliary air ejector aftercondenser and gland exhaust condenser section 35. The total condensate then flows through the passes of that section and the first stage feed heater section 36.

Heating steam conducted from the low-pressure turbine bleeder 4| through the conduit 42 is directed across the tubes in said feed heater section 36. The drains therefrom pass through conduit 43, traverse the drain cooler 34, and discharge through conduits 44 and 45 with additional make-up feed to the main condenser 21|.`

For distilling fresh Water from sea Water there is provided a single effect evaporator unit 46 of the type shown in the United States patent to Worthen and Fox, No. 2,378,350, issued June 12, 1945. Heating steam from the low-pressure turbine bleeder 4I is supplied through the conduit 41 to tubes in the evaporating section 48, draining through the conduit 49 to the auxiliary condenser 29. Steam from the 400 pound line I1 is further reduced in pressure by the reducing valve 50, and

is supplied through the conduits I, 52, 53, 54, 55, 56 and 51 to the air ejector jets 58, 59, 60 and 6|. Drains from the main and auxiliary air intercondensers 33 and 32 pass through the conduits 62 and B3 to the main and auxiliary condensers 24 and 29.

Exhaust steam from the turbine and turbogenerator glands 64, 65, 66 and 61 is conducted by means of conduits 68 and 69 and 10 to the gland exhaustl condenser 35. Drains from the gland exhaust condenser 35 and from the airejectorl condenser 1I of the evaporator 46 pass 4 through conduits 12 and 13 to the feed water drain collecting tank 30, the outlet, of which connects to conduit 45 and main condenser 24.

Feed from the first stage feed heater 36 is conducted through the conduit 14 and vent condenser section 15 to the second stage deaerating feed heater 3|, which is heated by steam taken from the bleeder connecting line 22 between the outlet of the intermediate pressure turbine 2| and the inlet of the low pressure reheater 9 by the conduit 16.

The turbine-driven feed pump I2 draws feed from the second stage feed heater 3| through the conduit 11 and discharges it through the conduit 18 to the two succeeding stages of high pressure feed heating, which receive the feed pump discharge at about 245 F. and discharge the heated feed at about 380 F. to the economizer I4.

The third and fourth stage feed heaters 19 and 80, which comprise the high pressure feed heating system, are connected in series by the conduit 8| and discharge through the conduit 82 to the economizer I4 as aforesaid. Heating steam for the third stage feed heater 19 is taken through the conduitl 83 from the intermediate-pressure tur-l bine bleeder 84, and for the fourth stage feed heater is taken from between the outlet of the high pressure turbine 1 and the high pressure reheater 8 by the conduit 85.

Both the third and the fourth stage feed heaters 19 and 80 are provided with integral drain coolers 86 and 81. Fourth stage feed heater drains discharge through the conduit 88 to the third stage feed heater 19, and the total drains from both these feed heaters discharge through the conduit 89 to the second stage feed heater 3|.

A portion of the relatively cold water (about 245 F.) from the discharge of the feed pump I2 is introduced through the conduit 90 into the throttle bushings of the reheater drain pumps 25 and 26 and returned through the conduit 9| to the second stage feed heater 3|. This serves to lubricate the bushings as Well as to prevent the erosion which Would occur if the reheater drains were permitted to ash through. 4

The pounds per square inch auxiliary system shown in Fig. 2 supplies motive steam to all steam driven deck auxiliaries and in addition furnishes heating steam to fuel oil heaters, galley, and shipsY heating system, which for convenience may be grouped together as the steam consumers 92. As shown, the system comprises a low pressure steam generator 93, a drain cooler 94, and a combined atmospheric condenser, contaminated drain inspection tank and hotwell 95, together with the associated feed pumps 96 and 91, pressure regulators 98 and 99, and float level controllers |00 and |0|. Y

As shown in Fig. 3, the low pressure steam generator 93 is primarily a horizontal submerged tube evaporator or steam transformer of large capacity, enclosed within a steel container shell which comprises the cylindrical casing |02, the front head |03 having a cylindrical nozzle opening |04, and the rear head |05. 'I'he inlet-outlet head |06 is provided with a vent |01 and with a horizontal wall |08 which together with the front tube sheet |09 forms the inlet ||0 and the outlet |I|. An upper nest of tubes ||2 and a lower nest of tubes ||3 extend from the front tube sheet |09 to the rear tube sheet I4, and are supported intermediate the ends by a tube support plate ||5 secured to an upper baie plate I|6 which connects said tube sheets |09 and |I4. A cover head I I8 together with the rear tube sheet I4 forms a chamber I1 I. 1 with awhich :the :rearfends of all theltubes communicate. The-lower tznestiiof.' tubes;'|-| 3 is` lsloped downwardly toward the .outlet :end :to

facilitate the discharge. oflcondensates. A lozw pressuresteam outlet A| I8 connected to .the .dry pipe 9, surface. andbottorn blow-off pipes and |.2 a perforatedl feed distributing pipe v.| 22; located beneath the tube nest .|.I3,.ailangeconnection |23. for a'relief valve|23', andan .access manhole |24 are also provided. f.: p

.As fshown diagrammatically inliig. :2, heating steam may be supplied .to-'theinlet .H0 .ofthe steam generator 93 from either the. 400..pounds per squareinch auxiliary 1ine..|1throughthecon duit |25 for operation in .rport when Vthe deck machinery .load is large, or through'theconduit 26.from.the highpressureturbine bleeder line 85 at approximately 185 pounds per'square inch'pres.- sure at vsea when the loadconsists largely offuehv oil heating and steam heating'. .Y

vSteam fromeither source is controlledjbythe pressure-regulating valves f98 .or 99 having .pressure-governingflines |21 and;|.28 connected to the shellof the steam generator 93. These .valves admit sufficient steam to the tube nests ||2 and |.|3 under varyingconditions to maintain the- Y ing and steam heatingunder all conditions and is especially useful during maneuvering when the bleeder pressure may drop below 125 pounds per square inch.

Tube nest drains are discharged through the conduit to the drain cooler 94, which also serves as a feed heater for heating the feed going to the steam generator 93.

The steam generator tube nest drain cooler 94 may be mounted on the base of the steam generator 93, and is a multi-pass unit with enclosing steel shells 94a and 94h and arranged for counterfiow with the tube nest drains inside and the steam generator feed outside the tubes 94o. External connections are made through the waterchest 94d. The drains from the low-pressure steam generator thus enter the drain inlet 94e make two passes through the tubes 94e, and exit through the drain outlet 941, while feed entering the feed inlet 94g is directed across the tubes counterow to the drains by means of the internal' division baille plates 94h and leave through feed outlet 941'. A level is maintained in the drain pipe |30 from the steam generator 93 to the drain cooler 94 by means of the float control |00 actuating the drain regulating valve |3| which controls the drains discharging from the drain cooler 94 through the conduit |32 to the second stage deaerating feed heater 3| in the main feed system. The high pressure steam and drains are thus completely isolated from the low pressure 125 pounds per square inch system.

The primary function of the drain cooler 94 is to cool the drains before they discharge to the deaerating feed heater 3|, thereby reducing the amount of ash vapor released by the drains as ythey are reduced to the temperature and pressure of that'unit. vUnder port conditions,-when the load on the :steam generator 93 isfheavy andthe .load on the dea'erating feed heater 3| is light, there is a, possibility of .excess flash .vapor fromthe drains causing :the relief valve of said deaerating .feed,heater.3| .to blow. Toremedy this-conditionne, yby-.pass line |33 visfprovided for, by-passing .steamgenerator .feed .to the atmos.

pheric condenser. 95, thereby cooling the. drains stillfurther Yand.;r.educ ing thefflash to-a quantity` which :the deaerating :feed i heater 3 canA handle.j

'.The combined atmosphericcondenser. and hot-- well .95.receives :through the conduits |341and |35v and aweilr |43 discharging to thereservoir or hotwell |39.

YTwo feed ,pumps areprovided in parallel in the low pressure system, one .the small .capacity electric Vfeed pump 98 for use at sea, and :the other the steam-driven double-acting .duplex feedpump 91,.'of large capacity for `use import. The feed pumps take suctionfrom the hotwell |39 of the combined atmospheric condenser `.95

through the conduit |44 and discharge through the conduit |45 and the drain'cooler 94 tothe feed distributing pipe |22 inthesteam generator shell. Steam to operate thesteam-driven'feed pump 91 isvtaken from the 125 .pound steam generator 93 itself. The water level in the steam generator shell is maintained by the float level controller |9| which operates'a by-pass .valve |46 to the pump'discharge line |45 to by-pass excess feed back to the atmospheric .condenser v95, and which also operates a throttle valve |41 in the steam supply line |48 to the steam feed pump 91. Make-up feed is suppliedv to the inspection tank |38 through the valve |49 from the fresh water drain tank 30.

From the foregoing description it will be understood that our invention may be regarded as having two distinct aspects: as an isolated low pressure steam generating system, complete in itself and employing an evaporator, drain cooler, atmospheric condenser and automatic controls; or as it is tted into the ships main cycle, from which the heating steam is taken and to which the cooled drains are returned with a minimum of disturbing effect.

The system is applicable to any size of ship and in any capacity of steam output which may be required.

Although We have described our invention hereinabove in considerable detail, we wish it to be understood that the present disclosure is illustrative, rather than restrictive, and that modifications, substitutions and equivalents may be resorted to without departing from the spirit or scope of the appended claims.

In accordance with statute, we claim the following as our invention:

1. A low pressure steam generating system comprising a high pressure steam operated prime mover, an evaporator receiving steam exhausted from said prime mover and having means for condensing saidv steam and for evaporating water thereby, an auxiliary source of intermediate steam pressure, and a reducing valve connected thereto and arranged kto supply supplemental steam'torthe evaporator when the pressure of the exhaust steam from the prime mover falls below a predetermined level. Y Y

2. A` steam generating system comprising a steam` operated prime mover,Y an evaporator recevingsteam exhausted from said prime'mover and having means for condensingsaid steam and for evaporatingV Water thereby, means responsive to the'pressure within the evaporatornforcontrolling the admission ofsteam to maintainsuch pressure'.substantially constant, a drain cooler cooling the drains `from the evaporator, `a condenser receiving and condensing the exhaust, and pumps forcing the condensate from the condenser to the drain cooler to cool the Yevaporator drains.

3.- 'vIhe combination with a high pressure boiler and a turbine connected tovreceive'steam therefronnof a low pressure Vsteam generator connected'to receive heating steam from said turbine,l v

a vdrain cooler connected to receive drainsrfr0msaid steam generator and to return them to the high pressure boiler feed, steam consumers con-AK nected to receive and utilize loW pressure steam ceiving said low pressure steam, a drain cooler receiving the drains from the steam generator and heating the feedgoing to the steam generator, a level controller regulating the discharge of the drains to the deaerating feed heater, a

combined condenserand hotwell receiving ex haust from the steam consumers, and ypumping -means withdrawing feed from the hotwell and discharging vthe feed through the Vdrain f cooler to the steam generator.

5. The combination with a high pressure'iboiler and a pressure reducing valve connected to de-v liver steam therefrom, of a low pressure steam generator connected to receive heatingY steam' v feed back to the condensing means, and autofrom the steaml generator, condensing means connectedvto-receive'the exhaust from the steam Y consumers,- an inspection tank and hotwell connectd--toreceive and store condensate therefrom,

pumping means connected to force feed from the generator, and -means for controlling the pump- 3'0 hotwellthrough thedrain cooler to the steam ing means in response to the level of liquid in'v the steam generator. Y

4. The combination with a high pressure boiler receiving feed from a deaerating feed heater, of a low pressure steam generator having tube nests in an enclosing shell and evaporating water within the shell to 10W pressure steam by means of high pressure steam circulated through the tube nests, a plurality of steam consumers rematic means for, controlling the amount of: feed by-passed in response to the level of feed in the steam generator.Y Y l EUGENE PORTER WORTHEN.

BENJAMIN FOX.

REFERENCES CITED The following references are of record in the le of this patent: Y v

UNITED STATES PATENTS Number Name Date 1,044,693 Schmidt Nov. 19, 1912 1,632,575 Abendroth June 14, 1927 1,712,992 Herrmann May 14, 1929' 1,938,366 Armacost Dec. 5, 1933 

